1. Field of the Invention
This invention relates generally to communication systems, and, more particularly, to circuitry and a concomitant methodology for transceiving a uniform data stream and a bursty data stream in a single interleaved stream.
2. Description of the Background
Currently communications service providers are focusing their attention on modems that operate in the multi-megabit range. For instance, CATV companies are planning to provide such high-speed modem service by grouping several customers so that they share a common channel that might otherwise be used only for an entertainment video service. This bus arrangement takes advantage of the bursty nature of modem traffic. Modem users are anticipated to need data at high rates for only very short periods of time, with relatively long quiescent periods between data bursts, so that the average data rate for any one user is much lower than the maximum rate that the user might occasionally require. Moreover, if the data is packetized, users could invoke the service for as little as the duration of one packet in a given instance of system use, which might be less than a kilobit of data. However, it is important in many applications that the delay in transmission and transmission processing of the data be minimal because the data being transmitted might be involved in an interactive process. These characteristics of bursty-type data transmission permit so-called statistical multiplexing of a data bus.
On the other hand, there are many communication services which have characteristics that are essentially opposite from those of aforementioned bursty data transmission characteristics. For example, entertainment video services are quite insensitive to even relatively long transmission delays, but it is important that a bit stream representing a digital version of a video signal not be interrupted once the user has started viewing an intelligible sequence. The same is also true of other services, such as the transmission of a long file to a waiting database. In this type of communications system, the data rate is essentially constant and the average data rate and maximum data rate on the medium are very close if not equal. For such systems, a bus arrangement is inappropriate unless many users are using the same data (broadcast mode), as in a CATV network. Hence, such systems are typically configured in a star or bus/star network.
Representative of prior art for controlling data flow over a transmission medium is U.S. Pat. No. 4,995,056 issued to Fogg et al. (Fogg). In Fogg, a sending system and a receiving system have multiple data buffers. The receiving system informs the sending system, in response to a sending system request, of the number of empty data buffers in the receiving system. The sending system can then propagate no more than the number of bits that will fill the empty receiver buffers. After the receiving system empties a number of buffers, the receiving system sends this information to the sending system. The receiving system and the sending system alternately communicate the number of empty receive data buffers and data bits to fill the buffers.
The art is devoid of teachings or suggestions wherein, given the contrasting requirements of a uniform data stream arising from such services as entertainment-type video services and the bursty data stream emanating from modem-type traffic, the uniform data stream and bursty data stream are synergistically combined in a transmitter into a single, interleaved data stream for communication over a given transmission medium, and separated in a receiver into the uniform stream and the bursty stream for use by the customer.